US3333257A - Measuring apparatus for driving a synchronous motor in response to the movement of acyclic wave pattern - Google Patents

Measuring apparatus for driving a synchronous motor in response to the movement of acyclic wave pattern Download PDF

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Publication number
US3333257A
US3333257A US393053A US39305364A US3333257A US 3333257 A US3333257 A US 3333257A US 393053 A US393053 A US 393053A US 39305364 A US39305364 A US 39305364A US 3333257 A US3333257 A US 3333257A
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United States
Prior art keywords
pattern
phase
movement
rotor
extent
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Expired - Lifetime
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US393053A
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English (en)
Inventor
Shepherd Alexander Turnbull
Taylor Lockhart
Walker Donald Ferguson
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Ferranti International PLC
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Ferranti PLC
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/36—Forming the light into pulses
    • G01D5/363—Direction discrimination
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
    • G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
    • G01B21/06—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness specially adapted for measuring length or width of objects while moving
    • G01B21/065—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness specially adapted for measuring length or width of objects while moving for stretchable materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/36—Forming the light into pulses

Definitions

  • Field of the invention relates to measuring apparatus for determining the extent and sense of the movement of a first object in one or other of two opposite directions with respect to a second object, and is a modification of the inventionhereinafter referred to as the parent in+ vention-disclosed in U.S. Patent No. 2,886,717, corresponding to British patent specification No. 760,321.
  • measuring apparatus for determining the extent and sense of the relative movement of a first object in one or other of two opposite directions with respect to a second object including means for setting up a cyclic wave pattern adapted to move with respect to said second object in dependence on the said relative movement of said first object, two detecting devices adapted during the said movement of the pattern to respond electrically to the conditions of the patern at two positions fixed with respect to the second object where said conditions are out of phase with one another by a fraction of half the cyclic wavelength of the pattern, and electrical stages for determining the sense of the said relative movement of said'object from the relative phase of the electrical output signals from'said detecting devices and for determining the extent of said movement from the number of cycles of said output signals which occur during said movement.
  • An object of the present invention is to provide measuring apparatus for the purpose stated in which the stabilisation of such factors is rendered unnecessary by the use of only three detecting devices.
  • FIGURE 1 is a schematic circuit diagram of one embodiment of the invention.
  • FIGURES 2 and 3 are circuit diagrams of stages shown generally in FIGURE 1.
  • stabilising stage 205 which stabilises the signals against in-phase disturbances of them in a manner to be described.
  • the three-phase output signals from stabiliser 205 are applied overleads P, Q, and R to the inputs of a power amplifier stage 230. To ensure stabilisation the stage is similar to stage 205 and so need not be depicted in detail.
  • the three-phase output from the amplifier is applied by way of leads P Q and R and phase-splitter stages 231 to 233 respectively to drive the three-phase stator windings 235 to 237 respectively of the motor 240.
  • the rotor 241 which is of the permanent-magnet two-pole kind usual with such motors, is coupled to some sort of device 242 responsive to the extent and direction of the rotation of the rotor.
  • the device 242 may take the form of a reversible revolution-counter or a pen driven by the rotor in one or other direction across a moving chart.
  • the motor rotor 241 rotates, representing by the exent and direction of its angular movement from some datum position the extent and direction of the movement of the worktable.
  • Stabilising stage 205 may take the form shown in FIGURE 2.
  • an amplifier triode valve 206, 207, or 208 for each of the three phases there is provided an amplifier triode valve 206, 207, or 208, as the case may be.
  • the cathodes of the valves are connected to earth through a resistor 215 common to all three of the valve input circuits.
  • the anodes of the valves are connected to a source of positive potential through load resistors 216 to 218 respectively and to amplifier stage 230 by way of leads P, Q, and R above mentioned.
  • Detecting devices 211 to 213 are connected to the respective grids of the valves.
  • stage 205 results from the use of the common cathode resistor 215 and the well-known fact that in a balanced three-phase system the sum of the respective phase currents at any given moment is zero.
  • the current through resistor 215 is a steady direct current as determined by the valve circuit parameters, there being no feedback voltage at signal frequency developed across it.
  • stage 205 is direct-current coupled; as explained in U.S. Patent No. 2,886,718, such a coupling is required to enable the apparatus to maintain a response condition appropriate to the position reached by the work table whenever it ceases to move, thereby enabling the apparatus to resume its correct functioning as soon as the table starts to move again.
  • the phase-splitter stages 231, 232 and 233 are used because it is desirable to eliminate direct-current components from the stator windings 235, 236 and 237 of motor 240 in order to ensure that the motor operates smoothly down to low speeds.
  • the stage includes two triode valves 243 and 244 sharing a common cathode load 245 and having separate anode load resistors 246 and 247.
  • Lead P is connected to the control grid of valve 243, the grid of valve 244 being earthed through a resistor 248.
  • the two parts of winding 235 are connected in series between the anodes of the valves.
  • the stage operates in known manner to apply to the windings an alternating push-pull voltage about a mean value which occurs when the valves are equally energised and hence is zero.
  • the lag of synchronous motor 240 should be limited to a low angle, say about degrees, and the motor should be capable of working down to zero frequency. To give a sufiiciently uniform rotation at such low speeds the pole slots in the stator laminations should be skewed, or the stator poles should be unslotted, and the currents which energise the stator windings should have the direct-current components eliminated.
  • the pattern may be an optical pattern set up by illuminated skewed gratings such as, for example, described in Patent No. 2,886,717. Owing to the skewed relationship of the gratings shown therein, with reference to FIGS. 1 and 2 of that patent, there is produced a cyclic coincidence pattern of alternate opacities and transparencies.
  • the pattern moves in a direction normal to the direction of movement of one grating, which moves relative to the other grating.
  • the relative phase of the parts of the patterns 2&1 and 203 seen by the three detecting devices 211 to 213, now photocells, may be adjusted by rotating one grating with respect to the other to obtain the required relationship.
  • a pattern denotes a spatial relationship depicted by plotting some characteristics such as light intensity against distance from a datum position. Since a pattern must fully exist at any given moment, the optical pattern set up by the gratings is a cyclic wave spatial pattern having a spatial wavelength between maximum intensities as more fully described in the aforesaid U.S. Patent No. 2,886,717.
  • the present invention is applicable not only where the pattern is of the optical kind but also where the pattern is of the recorded magnetic kind described in U.S. Patent No. 2,886,717.
  • Measuring apparatus for determining the extent and sense of the relative movement of a first object in one or other of two opposite directions with respect to a second object including means for setting up a cyclic wave pattern having a spatial wavelength between maximum intensities adapted to move with respect to the second object in dependence on the said relative movement of the first object and wherein the conditions of the pattern at three positions along said wavelength fixed with respect to said second object are 120 degrees out of phase with one another, three detecting means operative to produce electrical output signals responsive to and indicative of the conditions of the pattern, one detecting means being positioned at each of said three positions, a stabilising means for stabilising the electrical output signals from said detecting devices against in-phase changes of those signals, a three-phase synchronous motor having a permanent magnet rotor and a plurality of stator windings and being of the type in which the angular position of the rotor is determined by the relative conditions of energisation of said stator windings and capable of working down to zero frequency, means for energising said three stator
  • said stabilising means includes three amplifier means each having an input circuit arranged to receive the electrical output from one of the detecting means and an impedance common to all three input circuits.
  • said stabilising means includes three amplifier means each having an input circuit arranged to receive the electrical output from one of the photocells and an impedance common to all three input circuits, and said means for energizing said stator windings from the electrical output signals of the three detecting means respectively by way of the stabilising means includes three phase splitter circuits each having an input circuit arranged to receive the electrical output from one of the stabilising stages and an output connected to one winding of the synchronous motor to apply to said winding an alternating push-pull voltage about a mean value.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Transform (AREA)
  • Transmission And Conversion Of Sensor Element Output (AREA)
US393053A 1960-09-01 1964-08-31 Measuring apparatus for driving a synchronous motor in response to the movement of acyclic wave pattern Expired - Lifetime US3333257A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB30110/60A GB914190A (en) 1960-09-01 1960-09-01 Improvements relating to measuring apparatus

Publications (1)

Publication Number Publication Date
US3333257A true US3333257A (en) 1967-07-25

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US393053A Expired - Lifetime US3333257A (en) 1960-09-01 1964-08-31 Measuring apparatus for driving a synchronous motor in response to the movement of acyclic wave pattern

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US (1) US3333257A (de)
CH (1) CH412354A (de)
GB (1) GB914190A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922654A (en) * 1974-03-01 1975-11-25 Rucker Control Systems Motion transducer and indicator
CN108092547A (zh) * 2018-02-26 2018-05-29 盐城工学院 一种双足型压电电磁混合式直线电机及电激励方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1266001B (de) * 1963-12-04 1968-04-11 Contraves Ag Vorrichtung zur Erhoehung der Messgenauigkeit bei optisch-elektrischen Messeinrichtungen

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE702102C (de) * 1936-11-28 1941-01-30 Emil Busch Akt Ges Optische In Einrichtung zur lichtelektrischen Fernanzeige der Stellung des Anzeigemittels eines Messgeraetes
US2418193A (en) * 1942-07-11 1947-04-01 Bendix Aviat Corp Self-synchronous motion reproducing system
US2546628A (en) * 1947-06-20 1951-03-27 C Electronics Developments Ltd Electronic amplifier for threephase current impulses
US2669628A (en) * 1950-01-05 1954-02-16 Westinghouse Electric Corp Liquid break circuit interrupter

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE702102C (de) * 1936-11-28 1941-01-30 Emil Busch Akt Ges Optische In Einrichtung zur lichtelektrischen Fernanzeige der Stellung des Anzeigemittels eines Messgeraetes
US2418193A (en) * 1942-07-11 1947-04-01 Bendix Aviat Corp Self-synchronous motion reproducing system
US2546628A (en) * 1947-06-20 1951-03-27 C Electronics Developments Ltd Electronic amplifier for threephase current impulses
US2669628A (en) * 1950-01-05 1954-02-16 Westinghouse Electric Corp Liquid break circuit interrupter

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922654A (en) * 1974-03-01 1975-11-25 Rucker Control Systems Motion transducer and indicator
CN108092547A (zh) * 2018-02-26 2018-05-29 盐城工学院 一种双足型压电电磁混合式直线电机及电激励方法

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Publication number Publication date
GB914190A (en) 1962-12-28
CH412354A (de) 1966-04-30

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